In the past the removal and the maintenance of self-feed air drills from drill assemblies used for repetitively drilling holes as part of a predetermined manufacturing routine has been a complex and time consuming process. To disassemble and remove a self-feed air drill from a drill assembly a main power air line to the self-feed air drill must be disconnected and then a cycle start signal air line and a retract/emergency-stop air line must be removed. Next, if so equipped, a locational light switch must be disconnected from the self-feed air drill. The locational light switch may be either an air or electric device of a type well known in the art. It will be appreciated that each step in the disassembly of the lines from the drill assembly requires a different size and/or type of tool.
After disassembly of each line from the drill assembly the drill is then removed. Depending on the drill mounting method, the drill may be removed by either removing a lock nut at the face or front of a drill mount, removing bolts that secure the drill mount to a subplate or removing the subplate and drill mount entirely. If either the drill mount or subplate is removed, a minimum of two locating dowel pins also must be extracted. Because the dowel pins are typically not easily accessible and are secured by an interference fit, removal of the dowel pins is very difficult. Furthermore, because the dowel pins are secured by an interference fit, the more frequent the dowel pins are removed the less accurate the interference fit becomes such that drilling reproducibility and accuracy are diminished.
In addition, all of the foregoing steps require the use of a wrench in combination with a tool to "break loose" various retaining bolts and/or nuts to extract the dowel pins. The use of a wrench in combination with a tool to "break loose" the bolts and/or nuts inherently jolts the mounting fixture which effects the position and alignment of the mounting fixture and the drill assembly with respect to the hole to be drilled. As a result, quite often, the location and alignment of the drill assembly must be reset once the drill is reinstalled on the mounting fixture. Accordingly, the disassembly, removal and reinstallation of the drill to the mounting fixture of the drill assembly is a time consuming labor intensive process which may take 4 hours or more to complete.
In view of the foregoing, it will be appreciated that there is a significant need for an improved drill assembly that may be quickly and easily disassembled for purposes of maintenance and/or replacement in the production environment. The present invention provides for the main power, cycle start, emergency start and limit switch lines as an integral part of the mounting fixture thereby simplifying the assembly and disassembly of a drill assembly. Furthermore, the present invention provides a means for releasably removing the drill from the drill mounting fixture such that the use of wrenches and the like are unnecessary thereby reducing the attendant jarring forces typically required to remove the drill and improving drilling accuracy and reproducibility.